The specific aim of the proposed project is to enhance our understanding of the influence of social policies (including welfare policies), community context factors, and individual, partner, and background influences on nonmarital childbearing and subsequent union formation. The four stages of the proposed project wilt produce important information about factors associated with: Stage1: the likelihood that unmarried women and men will have a birth outside of marriage; Stage 2: the transition to marriage and cohabitation among unmarried parents; Stage 3: the likelihood of remaining in a stable union over time; and Stage 4: changes over time in patterns of nonmarital childbearing and union formation among unmarried parents. The proposed project will incorporate an ecological perspective, which posits that fertility and family formation behaviors will be influenced by factors from multiple domains. We will examine characteristics of the relationship between the biological parents at the time of the birth for analyses of marriage and cohabitation among unmarried parents. Additional relationship characteristics will include measures of the parent-parent relationship, the parent-child relationship, attitudes and fertility intentions, and previous family formation experiences of biological parents. We incorporate a life-course framework to analyze month-by-month histories of partner characteristics, marital and cohabiting unions, and childbearing for two cycles of the National Survey of Family Growth (1995, 2002). We will also use a new national data set - the Early Childhood Longitudinal Study-Birth Cohort- to examine the relationship context of nonmarital childbearing and the processes of union formation and dissolution among unmarried parents. We will incorporate a new multi-level and multi-process modeling package (aML) in order to assess selection effects and endogeneity of decisions about unmarried parenthood, marriage, and cohabitation. In an era of continued reforms to welfare legislation, research and policy communities will benefit from our policy-relevant empirical research, which is based on theory and is grounded in the research literature.